I start today's lesson by having the students gather on the carpet area. I want them all to sit so that they can see me sitting in a chair.

"I am going to say a number and ask that you use your math hands, to represent the number. Let's do one together. If I say 24, what would you show. That's right, 2 groups of ten (flash ten fingers twice) and 4 ones. Now, I want you to try some more."

If time permits, I will also flash fingers to them and have them tell me how many I flashed. I have included a video, Math Hands, that captures this activity.

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Advanced Preparation: You will need to make enough copies of the Math Make 10 20 100 recording sheet. I would make enough for students to do multiple sheets during the lesson.

"I want to continue to focus on complements of ten and twenty and add complements of 100 for some of you. I have a new game to introduce to you today. It involves you using dice and the Math Make 10 20 100 recording sheet.

As you can see the numbers 10, 20 and 100 are at the top. You will circle the number that you are working on. I will assign each of you the complement that I want you to focus on to start with. If you are working with 10, you will use the 1-9 die. If you are working on 20, you will use a 1-20 die, and if you are working on 100, you will use the 10s and 1s place value die.

You roll the die and record the number that you rolled. Then you fill in the complement for the number you rolled (based on the complement you are working on). You continue to do this until you finish the sheet. Then I want you to bring it to me."

I have also included a video titled Introducing 10, 20, 100. This video captures who I introduced the game to my class.

The CCSS expects that 1st graders can fluently add within ten and demonstrate the ability to add with in 20 accurately (CCSS.MATH.CONTENT.1.OA.C.6). This activity also allows students the opportunity to demonstrate an understanding and fluency with complements of 100 (CCSS.MATH.CONTENT.2.NBT.B.5). This is a 2nd grade standard but many first graders can do this by this point of the year.

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Students will now play the game that was just described in the previous section. This game allows for natural differentiation because you can have students working in different complements. As students are working, you will want to notice how students are solving complements of 20 and 100. This will give you chance to see if students are using their knowledge of ten to solve 20 and 100.

I have included of Complements of 20 video. This is a video of a student working on finding complements of 20.

As students finish, you will have to determine if they should move onto the next number or continue to work on the current one that was assigned to them. One way that I judge is to ask them to orally give me complements of the number that they are working on. This way I can check for fluency. Remember, fluency is the goal with this lesson and unit.

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I will ask the students to meet me on the carpet and hand out their sheet for today's Mad Minute exercise. This routine was introduced in a previous lesson. Please check out the link to get a full overview of this routine.

I want to really focus on fact fluency and build upon the students ability to solve within ten fluently (CCSS.MATH.CONTENT.1.OA.C.6). I am going to use the Mad Minute Routine. This is a very "old school" routine, but I truly feel students need practice in performing task for fluency in a timed fashion. Students need to obtain fact fluency in order to have success with multiplicative reasoning. Students who don't gain this addition fact fluency by the end of 2nd grade tend to struggle with the multiplicative reasoning in third. Having this fluency also allows them to work on more complex tasks because the have the fact recall to focus on the higher level concepts.